8 files changed, 221 insertions, 91 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 0c8d97b56f34..3aa0b72b3b94 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -848,6 +848,7 @@ struct ext4_inode_info {
         atomic_t i_ioend_count; /* Number of outstanding io_end structs */
         /* current io_end structure for async DIO write*/
         ext4_io_end_t *cur_aio_dio;
+        atomic_t i_aiodio_unwritten; /* Nr. of inflight conversions pending */
 
         spinlock_t i_block_reservation_lock;
 
@@ -2119,6 +2120,15 @@ static inline void set_bitmap_uptodate(struct buffer_head *bh)
 
 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
 
+/* For ioend & aio unwritten conversion wait queues */
+#define EXT4_WQ_HASH_SZ         37
+#define ext4_ioend_wq(v)   (&ext4__ioend_wq[((unsigned long)(v)) %\
+                                            EXT4_WQ_HASH_SZ])
+#define ext4_aio_mutex(v)  (&ext4__aio_mutex[((unsigned long)(v)) %\
+                                             EXT4_WQ_HASH_SZ])
+extern wait_queue_head_t ext4__ioend_wq[EXT4_WQ_HASH_SZ];
+extern struct mutex ext4__aio_mutex[EXT4_WQ_HASH_SZ];
+
 #endif  /* __KERNEL__ */
 
 #endif  /* _EXT4_H */
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 63a75810b7c3..ccce8a7e94ed 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3174,9 +3174,10 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
                  * that this IO needs to convertion to written when IO is
                  * completed
                  */
-                if (io)
+                if (io && !(io->flag & EXT4_IO_END_UNWRITTEN)) {
                         io->flag = EXT4_IO_END_UNWRITTEN;
-                else
+                        atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten);
+                } else
                         ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
                 if (ext4_should_dioread_nolock(inode))
                         map->m_flags |= EXT4_MAP_UNINIT;
@@ -3463,9 +3464,10 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
                  * that we need to perform convertion when IO is done.
                  */
                 if ((flags & EXT4_GET_BLOCKS_PRE_IO)) {
-                        if (io)
+                        if (io && !(io->flag & EXT4_IO_END_UNWRITTEN)) {
                                 io->flag = EXT4_IO_END_UNWRITTEN;
-                        else
+                                atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten);
+                        } else
                                 ext4_set_inode_state(inode,
                                                      EXT4_STATE_DIO_UNWRITTEN);
                 }
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 2e8322c8aa88..7b80d543b89e 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -55,11 +55,47 @@ static int ext4_release_file(struct inode *inode, struct file *filp)
         return 0;
 }
 
+static void ext4_aiodio_wait(struct inode *inode)
+{
+        wait_queue_head_t *wq = ext4_ioend_wq(inode);
+
+        wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_aiodio_unwritten) == 0));
+}
+
+/*
+ * This tests whether the IO in question is block-aligned or not.
+ * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
+ * are converted to written only after the IO is complete.  Until they are
+ * mapped, these blocks appear as holes, so dio_zero_block() will assume that
+ * it needs to zero out portions of the start and/or end block.  If 2 AIO
+ * threads are at work on the same unwritten block, they must be synchronized
+ * or one thread will zero the other's data, causing corruption.
+ */
+static int
+ext4_unaligned_aio(struct inode *inode, const struct iovec *iov,
+                   unsigned long nr_segs, loff_t pos)
+{
+        struct super_block *sb = inode->i_sb;
+        int blockmask = sb->s_blocksize - 1;
+        size_t count = iov_length(iov, nr_segs);
+        loff_t final_size = pos + count;
+
+        if (pos >= inode->i_size)
+                return 0;
+
+        if ((pos & blockmask) || (final_size & blockmask))
+                return 1;
+
+        return 0;
+}
+
 static ssize_t
 ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
                 unsigned long nr_segs, loff_t pos)
 {
         struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
+        int unaligned_aio = 0;
+        int ret;
 
         /*
          * If we have encountered a bitmap-format file, the size limit
@@ -78,9 +114,31 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
                         nr_segs = iov_shorten((struct iovec *)iov, nr_segs,
                                               sbi->s_bitmap_maxbytes - pos);
                 }
+        } else if (unlikely((iocb->ki_filp->f_flags & O_DIRECT) &&
+                   !is_sync_kiocb(iocb))) {
+                unaligned_aio = ext4_unaligned_aio(inode, iov, nr_segs, pos);
         }
 
-        return generic_file_aio_write(iocb, iov, nr_segs, pos);
+        /* Unaligned direct AIO must be serialized; see comment above */
+        if (unaligned_aio) {
+                static unsigned long unaligned_warn_time;
+
+                /* Warn about this once per day */
+                if (printk_timed_ratelimit(&unaligned_warn_time, 60*60*24*HZ))
+                        ext4_msg(inode->i_sb, KERN_WARNING,
+                                 "Unaligned AIO/DIO on inode %ld by %s; "
+                                 "performance will be poor.",
+                                 inode->i_ino, current->comm);
+                mutex_lock(ext4_aio_mutex(inode));
+                ext4_aiodio_wait(inode);
+        }
+
+        ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
+
+        if (unaligned_aio)
+                mutex_unlock(ext4_aio_mutex(inode));
+
+        return ret;
 }
 
 static const struct vm_operations_struct ext4_file_vm_ops = {
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 851f49b2f9d2..d1fe09aea73d 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -342,10 +342,15 @@ static struct kmem_cache *ext4_free_ext_cachep;
 /* We create slab caches for groupinfo data structures based on the
  * superblock block size.  There will be one per mounted filesystem for
  * each unique s_blocksize_bits */
-#define NR_GRPINFO_CACHES       \
-        (EXT4_MAX_BLOCK_LOG_SIZE - EXT4_MIN_BLOCK_LOG_SIZE + 1)
+#define NR_GRPINFO_CACHES 8
 static struct kmem_cache *ext4_groupinfo_caches[NR_GRPINFO_CACHES];
 
+static const char *ext4_groupinfo_slab_names[NR_GRPINFO_CACHES] = {
+        "ext4_groupinfo_1k", "ext4_groupinfo_2k", "ext4_groupinfo_4k",
+        "ext4_groupinfo_8k", "ext4_groupinfo_16k", "ext4_groupinfo_32k",
+        "ext4_groupinfo_64k", "ext4_groupinfo_128k"
+};
+
 static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
                                         ext4_group_t group);
 static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
@@ -2414,6 +2419,55 @@ err_freesgi:
         return -ENOMEM;
 }
 
+static void ext4_groupinfo_destroy_slabs(void)
+{
+        int i;
+
+        for (i = 0; i < NR_GRPINFO_CACHES; i++) {
+                if (ext4_groupinfo_caches[i])
+                        kmem_cache_destroy(ext4_groupinfo_caches[i]);
+                ext4_groupinfo_caches[i] = NULL;
+        }
+}
+
+static int ext4_groupinfo_create_slab(size_t size)
+{
+        static DEFINE_MUTEX(ext4_grpinfo_slab_create_mutex);
+        int slab_size;
+        int blocksize_bits = order_base_2(size);
+        int cache_index = blocksize_bits - EXT4_MIN_BLOCK_LOG_SIZE;
+        struct kmem_cache *cachep;
+
+        if (cache_index >= NR_GRPINFO_CACHES)
+                return -EINVAL;
+
+        if (unlikely(cache_index < 0))
+                cache_index = 0;
+
+        mutex_lock(&ext4_grpinfo_slab_create_mutex);
+        if (ext4_groupinfo_caches[cache_index]) {
+                mutex_unlock(&ext4_grpinfo_slab_create_mutex);
+                return 0;       /* Already created */
+        }
+
+        slab_size = offsetof(struct ext4_group_info,
+                                bb_counters[blocksize_bits + 2]);
+
+        cachep = kmem_cache_create(ext4_groupinfo_slab_names[cache_index],
+                                        slab_size, 0, SLAB_RECLAIM_ACCOUNT,
+                                        NULL);
+
+        mutex_unlock(&ext4_grpinfo_slab_create_mutex);
+        if (!cachep) {
+                printk(KERN_EMERG "EXT4: no memory for groupinfo slab cache\n");
+                return -ENOMEM;
+        }
+
+        ext4_groupinfo_caches[cache_index] = cachep;
+
+        return 0;
+}
+
 int ext4_mb_init(struct super_block *sb, int needs_recovery)
 {
         struct ext4_sb_info *sbi = EXT4_SB(sb);
@@ -2421,9 +2475,6 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
         unsigned offset;
         unsigned max;
         int ret;
-        int cache_index;
-        struct kmem_cache *cachep;
-        char *namep = NULL;
 
         i = (sb->s_blocksize_bits + 2) * sizeof(*sbi->s_mb_offsets);
 
@@ -2440,30 +2491,9 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
                 goto out;
         }
 
-        cache_index = sb->s_blocksize_bits - EXT4_MIN_BLOCK_LOG_SIZE;
-        cachep = ext4_groupinfo_caches[cache_index];
-        if (!cachep) {
-                char name[32];
-                int len = offsetof(struct ext4_group_info,
-                                        bb_counters[sb->s_blocksize_bits + 2]);
-
-                sprintf(name, "ext4_groupinfo_%d", sb->s_blocksize_bits);
-                namep = kstrdup(name, GFP_KERNEL);
-                if (!namep) {
-                        ret = -ENOMEM;
-                        goto out;
-                }
-
-                /* Need to free the kmem_cache_name() when we
-                 * destroy the slab */
-                cachep = kmem_cache_create(namep, len, 0,
-                                             SLAB_RECLAIM_ACCOUNT, NULL);
-                if (!cachep) {
-                        ret = -ENOMEM;
-                        goto out;
-                }
-                ext4_groupinfo_caches[cache_index] = cachep;
-        }
+        ret = ext4_groupinfo_create_slab(sb->s_blocksize);
+        if (ret < 0)
+                goto out;
 
         /* order 0 is regular bitmap */
         sbi->s_mb_maxs[0] = sb->s_blocksize << 3;
@@ -2520,7 +2550,6 @@ out:
         if (ret) {
                 kfree(sbi->s_mb_offsets);
                 kfree(sbi->s_mb_maxs);
-                kfree(namep);
         }
         return ret;
 }
@@ -2734,7 +2763,6 @@ int __init ext4_init_mballoc(void)
 
 void ext4_exit_mballoc(void)
 {
-        int i;
         /*
          * Wait for completion of call_rcu()'s on ext4_pspace_cachep
          * before destroying the slab cache.
@@ -2743,15 +2771,7 @@ void ext4_exit_mballoc(void)
         kmem_cache_destroy(ext4_pspace_cachep);
         kmem_cache_destroy(ext4_ac_cachep);
         kmem_cache_destroy(ext4_free_ext_cachep);
-
-        for (i = 0; i < NR_GRPINFO_CACHES; i++) {
-                struct kmem_cache *cachep = ext4_groupinfo_caches[i];
-                if (cachep) {
-                        char *name = (char *)kmem_cache_name(cachep);
-                        kmem_cache_destroy(cachep);
-                        kfree(name);
-                }
-        }
+        ext4_groupinfo_destroy_slabs();
         ext4_remove_debugfs_entry();
 }
 
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 7270dcfca92a..955cc309142f 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -32,14 +32,8 @@
 
 static struct kmem_cache *io_page_cachep, *io_end_cachep;
 
-#define WQ_HASH_SZ              37
-#define to_ioend_wq(v)  (&ioend_wq[((unsigned long)v) % WQ_HASH_SZ])
-static wait_queue_head_t ioend_wq[WQ_HASH_SZ];
-
 int __init ext4_init_pageio(void)
 {
-        int i;
-
         io_page_cachep = KMEM_CACHE(ext4_io_page, SLAB_RECLAIM_ACCOUNT);
         if (io_page_cachep == NULL)
                 return -ENOMEM;
@@ -48,9 +42,6 @@ int __init ext4_init_pageio(void)
                 kmem_cache_destroy(io_page_cachep);
                 return -ENOMEM;
         }
-        for (i = 0; i < WQ_HASH_SZ; i++)
-                init_waitqueue_head(&ioend_wq[i]);
-
         return 0;
 }
 
@@ -62,7 +53,7 @@ void ext4_exit_pageio(void)
 
 void ext4_ioend_wait(struct inode *inode)
 {
-        wait_queue_head_t *wq = to_ioend_wq(inode);
+        wait_queue_head_t *wq = ext4_ioend_wq(inode);
 
         wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_ioend_count) == 0));
 }
@@ -87,7 +78,7 @@ void ext4_free_io_end(ext4_io_end_t *io)
         for (i = 0; i < io->num_io_pages; i++)
                 put_io_page(io->pages[i]);
         io->num_io_pages = 0;
-        wq = to_ioend_wq(io->inode);
+        wq = ext4_ioend_wq(io->inode);
         if (atomic_dec_and_test(&EXT4_I(io->inode)->i_ioend_count) &&
             waitqueue_active(wq))
                 wake_up_all(wq);
@@ -102,6 +93,7 @@ int ext4_end_io_nolock(ext4_io_end_t *io)
         struct inode *inode = io->inode;
         loff_t offset = io->offset;
         ssize_t size = io->size;
+        wait_queue_head_t *wq;
         int ret = 0;
 
         ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
@@ -126,7 +118,16 @@ int ext4_end_io_nolock(ext4_io_end_t *io)
         if (io->iocb)
                 aio_complete(io->iocb, io->result, 0);
         /* clear the DIO AIO unwritten flag */
-        io->flag &= ~EXT4_IO_END_UNWRITTEN;
+        if (io->flag & EXT4_IO_END_UNWRITTEN) {
+                io->flag &= ~EXT4_IO_END_UNWRITTEN;
+                /* Wake up anyone waiting on unwritten extent conversion */
+                wq = ext4_ioend_wq(io->inode);
+                if (atomic_dec_and_test(&EXT4_I(inode)->i_aiodio_unwritten) &&
+                    waitqueue_active(wq)) {
+                        wake_up_all(wq);
+                }
+        }
+
         return ret;
 }
 
@@ -190,6 +191,7 @@ static void ext4_end_bio(struct bio *bio, int error)
         struct inode *inode;
         unsigned long flags;
         int i;
+        sector_t bi_sector = bio->bi_sector;
 
         BUG_ON(!io_end);
         bio->bi_private = NULL;
@@ -207,9 +209,7 @@ static void ext4_end_bio(struct bio *bio, int error)
                 if (error)
                         SetPageError(page);
                 BUG_ON(!head);
-                if (head->b_size == PAGE_CACHE_SIZE)
-                        clear_buffer_dirty(head);
-                else {
+                if (head->b_size != PAGE_CACHE_SIZE) {
                         loff_t offset;
                         loff_t io_end_offset = io_end->offset + io_end->size;
 
@@ -221,7 +221,6 @@ static void ext4_end_bio(struct bio *bio, int error)
                                         if (error)
                                                 buffer_io_error(bh);
 
-                                        clear_buffer_dirty(bh);
                                 }
                                 if (buffer_delay(bh))
                                         partial_write = 1;
@@ -257,7 +256,7 @@ static void ext4_end_bio(struct bio *bio, int error)
                              (unsigned long long) io_end->offset,
                              (long) io_end->size,
                              (unsigned long long)
-                             bio->bi_sector >> (inode->i_blkbits - 9));
+                             bi_sector >> (inode->i_blkbits - 9));
         }
 
         /* Add the io_end to per-inode completed io list*/
@@ -380,6 +379,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 
         blocksize = 1 << inode->i_blkbits;
 
+        BUG_ON(!PageLocked(page));
         BUG_ON(PageWriteback(page));
         set_page_writeback(page);
         ClearPageError(page);
@@ -397,12 +397,14 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
         for (bh = head = page_buffers(page), block_start = 0;
              bh != head || !block_start;
              block_start = block_end, bh = bh->b_this_page) {
+
                 block_end = block_start + blocksize;
                 if (block_start >= len) {
                         clear_buffer_dirty(bh);
                         set_buffer_uptodate(bh);
                         continue;
                 }
+                clear_buffer_dirty(bh);
                 ret = io_submit_add_bh(io, io_page, inode, wbc, bh);
                 if (ret) {
                         /*
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 48ce561fafac..f6a318f836b2 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -77,6 +77,7 @@ static struct dentry *ext4_mount(struct file_system_type *fs_type, int flags,
                        const char *dev_name, void *data);
 static void ext4_destroy_lazyinit_thread(void);
 static void ext4_unregister_li_request(struct super_block *sb);
+static void ext4_clear_request_list(void);
 
 #if !defined(CONFIG_EXT3_FS) && !defined(CONFIG_EXT3_FS_MODULE) && defined(CONFIG_EXT4_USE_FOR_EXT23)
 static struct file_system_type ext3_fs_type = {
@@ -832,6 +833,7 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
         ei->i_sync_tid = 0;
         ei->i_datasync_tid = 0;
         atomic_set(&ei->i_ioend_count, 0);
+        atomic_set(&ei->i_aiodio_unwritten, 0);
 
         return &ei->vfs_inode;
 }
@@ -2716,6 +2718,8 @@ static void ext4_unregister_li_request(struct super_block *sb)
         mutex_unlock(&ext4_li_info->li_list_mtx);
 }
 
+static struct task_struct *ext4_lazyinit_task;
+
 /*
  * This is the function where ext4lazyinit thread lives. It walks
  * through the request list searching for next scheduled filesystem.
@@ -2784,6 +2788,10 @@ cont_thread:
                 if (time_before(jiffies, next_wakeup))
                         schedule();
                 finish_wait(&eli->li_wait_daemon, &wait);
+                if (kthread_should_stop()) {
+                        ext4_clear_request_list();
+                        goto exit_thread;
+                }
         }
 
 exit_thread:
@@ -2808,6 +2816,7 @@ exit_thread:
         wake_up(&eli->li_wait_task);
 
         kfree(ext4_li_info);
+        ext4_lazyinit_task = NULL;
         ext4_li_info = NULL;
         mutex_unlock(&ext4_li_mtx);
 
@@ -2830,11 +2839,10 @@ static void ext4_clear_request_list(void)
 
 static int ext4_run_lazyinit_thread(void)
 {
-        struct task_struct *t;
-
-        t = kthread_run(ext4_lazyinit_thread, ext4_li_info, "ext4lazyinit");
-        if (IS_ERR(t)) {
-                int err = PTR_ERR(t);
+        ext4_lazyinit_task = kthread_run(ext4_lazyinit_thread,
+                                         ext4_li_info, "ext4lazyinit");
+        if (IS_ERR(ext4_lazyinit_task)) {
+                int err = PTR_ERR(ext4_lazyinit_task);
                 ext4_clear_request_list();
                 del_timer_sync(&ext4_li_info->li_timer);
                 kfree(ext4_li_info);
@@ -2985,16 +2993,10 @@ static void ext4_destroy_lazyinit_thread(void)
          * If thread exited earlier
          * there's nothing to be done.
          */
-        if (!ext4_li_info)
+        if (!ext4_li_info || !ext4_lazyinit_task)
                 return;
 
-        ext4_clear_request_list();
-
-        while (ext4_li_info->li_task) {
-                wake_up(&ext4_li_info->li_wait_daemon);
-                wait_event(ext4_li_info->li_wait_task,
-                           ext4_li_info->li_task == NULL);
-        }
+        kthread_stop(ext4_lazyinit_task);
 }
 
 static int ext4_fill_super(struct super_block *sb, void *data, int silent)
@@ -4768,7 +4770,7 @@ static struct file_system_type ext4_fs_type = {
         .fs_flags       = FS_REQUIRES_DEV,
 };
 
-int __init ext4_init_feat_adverts(void)
+static int __init ext4_init_feat_adverts(void)
 {
         struct ext4_features *ef;
         int ret = -ENOMEM;
@@ -4792,23 +4794,44 @@ out:
         return ret;
 }
 
+static void ext4_exit_feat_adverts(void)
+{
+        kobject_put(&ext4_feat->f_kobj);
+        wait_for_completion(&ext4_feat->f_kobj_unregister);
+        kfree(ext4_feat);
+}
+
+/* Shared across all ext4 file systems */
+wait_queue_head_t ext4__ioend_wq[EXT4_WQ_HASH_SZ];
+struct mutex ext4__aio_mutex[EXT4_WQ_HASH_SZ];
+
 static int __init ext4_init_fs(void)
 {
-        int err;
+        int i, err;
 
         ext4_check_flag_values();
+
+        for (i = 0; i < EXT4_WQ_HASH_SZ; i++) {
+                mutex_init(&ext4__aio_mutex[i]);
+                init_waitqueue_head(&ext4__ioend_wq[i]);
+        }
+
         err = ext4_init_pageio();
         if (err)
                 return err;
         err = ext4_init_system_zone();
         if (err)
-                goto out5;
+                goto out7;
         ext4_kset = kset_create_and_add("ext4", NULL, fs_kobj);
         if (!ext4_kset)
-                goto out4;
+                goto out6;
         ext4_proc_root = proc_mkdir("fs/ext4", NULL);
+        if (!ext4_proc_root)
+                goto out5;
 
         err = ext4_init_feat_adverts();
+        if (err)
+                goto out4;
 
         err = ext4_init_mballoc();
         if (err)
@@ -4838,12 +4861,14 @@ out1:
 out2:
         ext4_exit_mballoc();
 out3:
-        kfree(ext4_feat);
+        ext4_exit_feat_adverts();
+out4:
         remove_proc_entry("fs/ext4", NULL);
+out5:
         kset_unregister(ext4_kset);
-out4:
+out6:
         ext4_exit_system_zone();
-out5:
+out7:
         ext4_exit_pageio();
         return err;
 }
@@ -4857,6 +4882,7 @@ static void __exit ext4_exit_fs(void)
         destroy_inodecache();
         ext4_exit_xattr();
         ext4_exit_mballoc();
+        ext4_exit_feat_adverts();
         remove_proc_entry("fs/ext4", NULL);
         kset_unregister(ext4_kset);
         ext4_exit_system_zone();
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 9e4686900f18..97e73469b2c4 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -473,7 +473,8 @@ int __jbd2_log_space_left(journal_t *journal)
 }
 
 /*
- * Called under j_state_lock.  Returns true if a transaction commit was started.
+ * Called with j_state_lock locked for writing.
+ * Returns true if a transaction commit was started.
  */
 int __jbd2_log_start_commit(journal_t *journal, tid_t target)
 {
@@ -520,11 +521,13 @@ int jbd2_journal_force_commit_nested(journal_t *journal)
 {
         transaction_t *transaction = NULL;
         tid_t tid;
+        int need_to_start = 0;
 
         read_lock(&journal->j_state_lock);
         if (journal->j_running_transaction && !current->journal_info) {
                 transaction = journal->j_running_transaction;
-                __jbd2_log_start_commit(journal, transaction->t_tid);
+                if (!tid_geq(journal->j_commit_request, transaction->t_tid))
+                        need_to_start = 1;
         } else if (journal->j_committing_transaction)
                 transaction = journal->j_committing_transaction;
 
@@ -535,6 +538,8 @@ int jbd2_journal_force_commit_nested(journal_t *journal)
 
         tid = transaction->t_tid;
         read_unlock(&journal->j_state_lock);
+        if (need_to_start)
+                jbd2_log_start_commit(journal, tid);
         jbd2_log_wait_commit(journal, tid);
         return 1;
 }
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index faad2bd787c7..1d1191050f99 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -117,10 +117,10 @@ static inline void update_t_max_wait(transaction_t *transaction)
 static int start_this_handle(journal_t *journal, handle_t *handle,
                              int gfp_mask)
 {
-        transaction_t *transaction;
-        int needed;
-        int nblocks = handle->h_buffer_credits;
-        transaction_t *new_transaction = NULL;
+        transaction_t   *transaction, *new_transaction = NULL;
+        tid_t           tid;
+        int             needed, need_to_start;
+        int             nblocks = handle->h_buffer_credits;
 
         if (nblocks > journal->j_max_transaction_buffers) {
                 printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n",
@@ -222,8 +222,11 @@ repeat:
                 atomic_sub(nblocks, &transaction->t_outstanding_credits);
                 prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
                                 TASK_UNINTERRUPTIBLE);
-                __jbd2_log_start_commit(journal, transaction->t_tid);
+                tid = transaction->t_tid;
+                need_to_start = !tid_geq(journal->j_commit_request, tid);
                 read_unlock(&journal->j_state_lock);
+                if (need_to_start)
+                        jbd2_log_start_commit(journal, tid);
                 schedule();
                 finish_wait(&journal->j_wait_transaction_locked, &wait);
                 goto repeat;
@@ -442,7 +445,8 @@ int jbd2__journal_restart(handle_t *handle, int nblocks, int gfp_mask)
 {
         transaction_t *transaction = handle->h_transaction;
         journal_t *journal = transaction->t_journal;
-        int ret;
+        tid_t           tid;
+        int             need_to_start, ret;
 
         /* If we've had an abort of any type, don't even think about
          * actually doing the restart! */
@@ -465,8 +469,11 @@ int jbd2__journal_restart(handle_t *handle, int nblocks, int gfp_mask)
         spin_unlock(&transaction->t_handle_lock);
 
         jbd_debug(2, "restarting handle %p\n", handle);
-        __jbd2_log_start_commit(journal, transaction->t_tid);
+        tid = transaction->t_tid;
+        need_to_start = !tid_geq(journal->j_commit_request, tid);
         read_unlock(&journal->j_state_lock);
+        if (need_to_start)
+                jbd2_log_start_commit(journal, tid);
 
         lock_map_release(&handle->h_lockdep_map);
         handle->h_buffer_credits = nblocks;